Process for producing fuel gas and carbonized coal



@CL `2, IQSLl W. :,AlRD 1,828,148

PROCESS FOR PRODUGING FUEL GAS AND CARBONIZED COAL Filed Feb. 1?,l 1923 WLeuR G LAIRD @moe/M1501:

Patented Oct. 20, 1,931

UNITED STATES PATENT OFFICE WILBUB G. LAIRD, F NEW YORK, N.. Y., ASSIGNOB. TO HEAT TREATING COMPANY, OF

NEW YORK, N. Y., A CORPORATION OF DELAWARE PROCESS FOR PRODUCING FUEL GAS AND CARBONIZED COAL Application filed February 16, 1923. Serial No. 619,375..

rihis invention relates to a process for making gas and particularly to a process by which a cold, clean gas may be made through the primary or partial combustion of coal or other fuel containing volatile hydrocarbons. if a fuel containing volatile hydrocarbons be employed in the common type of gas producer, in which the gas is formed by the primary combustion of the coal with air or air m and steam, the volatile constituents of the coal passageways for the gas become covered with 4it and can be cleared from it only with great Y difficulty, particularly if the pitch is subjected to contact with the hot gas and a long continued baking is thereby permitted to take place. Producer gas made in this manner must, accordingly, be maintained and used while suiiciently hot to plrevent the pitch from condensing out and t e field of usefulness of the gas is thereby restricted. To avoid 39 or lessen the difiiculties caused by the forma-- tion and deposition of pitch, coke may be used but, as coke is usually an expensive fuel and cooling the gas would lower the heat efficiency of the process, the advantages obtained by the use of coke are offset by other factors.

These defects and limitations are avoided by the present invention, one object of which is to provide al process by which a clean, cold, fuel gas of the producer type may be obtained from coal and similar fuels'containing volatile constituents.

A further object of the invention is to providea process for producing a fuel gas by the incomplete combustion of carbonaceous fuel in which the heat set free in said combustion is efficiently and effectively utilized in the gas making operations.

Further objects and features of the inven- 5@ tion are the utilization of fuels of various grades,` some of which might not be otherwise utilizable for gas making, the carbonization of such fuels under uniform and accurately controlled conditions with heat from the hot producer gas and in a manner to remove and recover a maximum of volatile products, the production of coke, the filtering of the producer gas and removal of pitch and other troublesome constituents Within the gas apparatus, and the recovery and utilization of the sensible heat of the products within the gas apparatus to maintain the most effective temperature conditions for the efficient production of gas and utilization of fuel.

With these and other objects in view, the invention comprises the process described and set forth in the following specification and claims.

The various features of the invention are illustrated in the accompanying drawings in which;

Fig. 1 is a sectional, diagrammatic, elevation of apparatus for making gas, embodying a preferred form of the invention, structural detiils being omitted for the sake of clearness, an

Fig. 2 is a sectional viewl of the apparatus illustrated in Fig. 1 above the producer and carbonizing retorts.

In the present invention, coal is carbonized by contact with hot gas from air/producer, serving at the same time to cool the gas and entra and retain any pitch or solids which ma be present in the hot gas. When the car onization of the coal is sufficiently complete, it may be supplied to the gas producer and the gas produced in this producer may then be used to carbonize coal to be used in the producer. In carbonizing the coal, the hot producer gases are passed through the coal in a. downward direction in such a manner that each layer of coal is first subjected to a low temperature carbonization by gases partly cooled in passing through the upper layers of the coal and are heated to pro ressively higher temperatures as the mass o coal heats up and as the final high temperature carbonizing zone passes downwardly through successively lower layers. The vaporized products of carbonization which may con 100 dense in the lower, cooler, portions of the coal tend to How away from the carbonizing zones, thereby avoiding their destruction or decomposition through contact with the hot carbonized product. The carbonization is carried out preferably in retorts of limited cross sectional area, a number of such retorts being arranged in parallel in the path of the producer gases and the passage of the gases therethrough being controlled to provide uniform treatment for the coal in each retort.

When the carbonization of the coal is completed, the resulting coke is at a very high temperature, that in the upper layers being near the temperature ot the hot producer gas. To utilize this heat and to chill the coke, steam is blown upwardly through the coke, being superheated in the lower portion of the retor't and, as it comes in contact with the upper, hotter portion of the body of coke, reacts therewith to form hydrogen and carbon dioxide or carbon monoxide. These gases are then passed through the producer and serve to increase the total of gas production, the gases leaving the producer being. in this stage of the operations, passed through a second or alternate set of retorts. As the producer gases generally contain more sensible heat than is required for the coal carbonizing operations and are at a much higher temperature than is required for carbonizing the coal, a portion of this heat is intercepted in suitable heat storing bodies between the producer and the carbonizing coal in the retorts and is returned to the producer in such a manner as to be applied to the endothermic reactions and to increasing the quantity of fuel gases produced, in the producer. When there is. an excess of hot producer gases over that re- 'quired in carbonizing the coal, the heat in a portion of the gases may be used entirely for increasing the production of gas in the producer by preheating the air supplied to the producer for combustion. Ey varying the quantity of air thus used, the quantity of heat supplied to the carbonizing coal may be controlled in accordance with the requirements of coals of different characteristics.

Referring, more particularly, to the accompanying drawings, a supply ot coal or colte, or coal previously carbonized in the process, 1s supplied from a hopper l() through a conveyor 1Q and chute l/-i to gas producer 16. The coke is received in Vertical shaft i8, eX- tending upwardly from above a combustion' Zone 2O of the producer, and descends gradually to the combustion zone as the colte is consumed. The coke is heated in its downward. passage through the shaft 'i8 by hot gases passing upwardly therctiiiougl from the combustien sone oi e producer a "d reaches the combustion ture able for comb In the eeinl to carbon bustle pipe 22 through branch pipes 24 in the usual manner. Some steam may be admitted to react with the hot coke to utilize some of the excess heat of the combustion for the production of additional quantities of gas. The slag resulting from the combustion is received in a receptacle 26 at the base of the producer and removed through a draw oli opening 28, a slagging type of producer being illustrated in the drawings by way of example.

A large portion of the hot producer gas formed in the combustionzone 20 is withdrawn, in alternate periods, either through a vertical passage 30 at the right of the shaft 18, and a horizontal passage 3Q to coking retorts 34, or through a vertical passage 36 at the opposite side of the shaft 18 and a horizontal passage 38 to an alternate set of coking retorts 40. The retorts 34 and 40 during their respective periods for the passage of the hot gas are kept filled with coal to be carbonized for use in the producer 16, the hot gases being preferably passed downwardly through the coal in the retorts.

As the hot producer gases come into contact with the bodies of coal, in retorts 34 for example, the gases are cooled by giving up their sensible heat to the coal. Any pitch which may be contained in the hot gases is thereby condensed, and as the mass of coal particles form an effective filtering medium, the pitch is caught on the coal and retained and later carbonized with the coal.

As the hot gases give up their heat the upper portions of the coal in the retorts 34 are rapidly brough to a carbonizing temperature and a quantity of hydrocarbon gases and coal distillation products are formed4 and carried through the retorts with the rapidly flowing producer gases. As the upper portions of the coal become completely carbonized. the lower portions of the coal are gradually heated and distilled, and the temperature required for complete carbonization is carried to the lower part of the retorts until the coal is carbonized to the desired extent. The coal tar, ammonia and other products of distillation are immediately removed from the distilling zone as soon as they are formed and carried through progressively cooler zones thereby avoiding any tendency for their subsequent decomposition and obtaining the products at 'their lowest temperature or' 'fob mation. Should any of these products be condensed by Contact with unheated portions or" the coal, there is no possibility 'of their falling baclt into the carboniaing noue s will tend to gravitate or e carried i'lowing gases progressively ci it the dimensions of '-tle c in the inc r would .oe n

tion of the retorts for an uneven carbonizing action due to the formation of chimneys .through unevenness in the character or size of the coal or in its packing in the retort. The retortsare accordingly kept within limits of cross sectional dimensions such that chimneys do not tend to form or, if formed, are of such dimensions that heat sufcient for carbonization may be transmitted sidewise through the coa-l in the retort with suiiicient facility to insure carbonization throughout all portions of the retorts. When producers of larger capacity are employed, therefore, the number of the retorts, rather than their size, is increased.

lin the embodiment of the invention shown in the drawings, four retorts are indicated `on each side of the producer and each retort is provided with an individual gas oli-take pipe 42 and a control Valve 44 for controlling the quantity of gas passing from each retort to a collecting main 46 and thus regulating the action of the retorts. Each retort is also provided with an individual charging door 48 in its top wall through which coal may besupplied from a travelling hopper 50. Ordinarily the tar produced in the retorts is sold but when this is not done, it may be sprayed onto the hot coke in the retorts through a spray pipe 52 and decomposed to gaseous products.

When the carbonization of the ,coal in the retorts is completed, the coalwill have been raised to a very high temperature, the temperature in the upper part of the retorts approaching that-of the hot producer gas. This heat is recovered when the producer gases are sent through the alternate retorts 40 by passing steam upwardly through the retorts and through the combustion zone of the producer. This steam is supplied through a pipe 54 and control valve 56 to a distributing ring 58 at the lower part of the retorts and, in passing upwardly through the retort, is superheated to a temperature at which it reacts with .the hot coke in the upper part of the retortv to form blue gas. This may be continued at a much lower temperature than would be desirable in a water gas apparatus since the objectionably large quantities of carbon dioxide formed at the lower temperatures are decomposed by heat from the combustion zone ofthe producer and transformed into carbon monoxide as the gases later pass through the producer. When the coke has been sufficiently cooled itis withdrawn through doors 60 in t-he bottoms of the retorts and quenched. It is then ready for use in the producer or for sale or other urposes. To keep the coke from contact wlth the steam distributing ring 58 it is preferably supported on a raised, perforated, supporting plate 61 mounted on the door 60.

The heat required to carbonize the coal is, in general, much less than the sensible heat carried by the gases obtained in the primary combustion of the coke produced. This eX- cess of heat produced in the-producer is decreased somewhat by the reduction of the quantity of coke through its combustion in the steaming of the retorts. To further decrease the excess of heat, checker brick 62 and 64 are provided in the passageways 30 and 36 through which heat may be absorbed and returned to the producer. When coal is being carbonized in the retorts 34, for example, the hot producer gases first come into contact with the checker work 62, reducing the temperature ofthe gases coming into contact with the coal in the upper part of the retorts, thus utilizing lower temperatures for the carbonizationwhile the checkerwork is being heated. As the carbonization continues, the temperature of the checkerwork increases until it approaches that of the hot producer gas. lhen the direction of flow of the gases is reversed during the steaming of the retorts 34 and the carbonization in retorts 40, the heat absorbed in the checkerwork 62 is absorbed by the gases passing to the producer and serves to heat these gases. That portion of the heat produced in the producer .which would ordinarily be used in heating these gases to the checkerbrick temperature is accordingly available" for the endothermic reactions such as the dissociation of steam in the producer,

thus increasing the quantity of gas produced Y through sensible heat abstracted from the hot producer gases. Similarly, the checkerwork 64 serves to abstract heat when coal is being carbonized in the retorts 40 and return it to the producer when the relation of the retorts is reversed. Through this arrangement, a portion of the heat of the producer gases lying between the temperature of the producer and the temperature of carbonization of the coal is abstracted from the gases in the checkerwork and in the previously carbonized coal and returned to the producer to be utilized in increasing the caloric value of the gas and the eiiiciency of conversion of the coal into gas.

In some cases the excess of heat in the producer gases may not be completely utilized in the manipulations outlined above, the eX- cess depending to some eaxtent on the type of coal used. In this case, a portion of the producer gases is withdrawn upwardly through the coke in the shaft 18, preheating this coke preparatory to its passage to the producer, and is then passed through a pipe or conduit 66 to a heat interchanger 69 indicated dia.- grammatically in the dra-wings. The hot gases pass through passages 69 in the interchanger and give up their heat through a diaphragm 70 to air in passages 72 in the interchanger. From the passages 72 the air is supplied to the bustle pipe 22 andthe combustion zone 20 'of the producer. Since the gases are somewhat cooled in the shaft 18 and are small in quantity in comparison with the air to be heated, the walls and diaphragm of the heat interchanger are at a suiiiciently low temperature to permit the use of heat resisting metal in its construction. The preheating of the air in this manner diminishes the quantity of heat used in the combustion Zone of the producer in heating the air to the reaction temperature 'and makes a larger quantity of heat available for the transformation of steam and carbon to hydrogen and carbon monoxide. The use of the heat interchanger may, however, be omitted and the gases passing upwardly through the shaft 18 may be passed to the passages 32 or 38 through passages 74 and 76 controlled by dampers as shown.

The retorts 40 are provided with gas outlets 80, control valves 82 and header 84 similar to those of retorts 34, and with a steam supply pipe 86 and distributing ring 88. Charging doors 90, coal hopper 92 and -tar sprays 94 are also provided. The area of the retorts-34 and 40 and the shaft 18 may be gradually enlarged downwardly to facilitate the downward passage of coal and coke and the removal of the carbonized coal. When necessary, the retorts may be jaclreted to maintain the walls hot and enable the coal adjacent the Walls to be completely carbonized.

The coal used in the process need not be limited to the special grades required for the production of coke but any suitable coal or other suitable fuel may be used. When the coal tends to become so pasty during carbonlzation as to materially impede'the passage of the producer gases, the coal may be mixed prior to or during the charging of the retorts with sufficient coke to provide the required porosity. A layer of coke 96, as indicated in the retort 40 in Fig. i, is preferably placed in the bottom of the retort to protect the doors and steam inlets from burning out or clogging with tar. v

The operation of the process and apparatus is briefly as follows:

Coke is supplied continuously through the shaft 18 to the combustion zone 2O of the producer and is burned to producer gas, by means of air or air and steam supplied through pipes 22 and 24. The hot producer gases are withdrawn through the passages 30 and 32 and the checkerwork 62 therein and passed downwardly through coal in the carbonizing retorts 34. The producer gases and products of the distillation of the coal are withdrawn through the outlet pi es 42. lVhen the coal in the retorts 34 is su ciently carbonized, steam is supplied to the lower part of the retorts through a pipe 54 and distributing ring 58 and passing upwardly through the retorts is superheated and transformed into carbon oxides and hydrogen. From the retorts the gases pass through the passages 32 and 30 and the hot checkerwork 62 and through the upper portion of the combustion zone 20 of the producer in which the completion of the transformation of the gases to hydrogen and carbon monoxide is accomplished. From the combustion zone the hot lgases pass through passages 36 and 38 and checkerwork 62 to the retorts 40 to carbonize charges of coal in these retorts. When the coal in' retorts 40 is carbonized and the coke in retorts 34 is cooled as much as practicable, the coke in retorts 34 is replaced with resh charges of coal and the passage'of gases is reversed. A portion of the gases produced in the combustion zone 20 are drawn upwardly through the shaft 18 heating the coke therein and passes to the heat interchanger 66 to preheat air supplied to the pipes 22 and 24. The heat of the partial combustion of the fuel is accordingly eiiiciently used in the gas producing apparatus for the production of gas and carbonization of coal and the gases are delivered in a suliciently oool condition for eiioient distribution without excessive waste of heat. It is to be understood that the cooled gases may be passed through any suitable tar extractors and scrubbing and purifying apparatus after leaving the retorts. The gases withdrawn through the pipes 46 and 84 may be blended With the gas Withdrawn through the pipe 66 when desired.

Having described the invention, what I claim and desire to secure by Letters Patent 1. A method of producing fuel gas and carbonizing coal which comprises continuously blasting solid carbonaceous fuel with air and thereby forming hot producer gas, passing the hot producer gas formed downwardly through stationary bodies of coal in retorts and thereby carbonizing the coal therein, withdrawing gases and vapors from the bottom of the retorts, diverting the course ot the hot producer gas from the producer through coal in a second set of retorts after the coal in coal gas and producer gas and for carbonizing coal which com rises continuously generatlng producer gas y continuously air-blasting a charge of solid carbonaceous fuel in a gas producer, periodically passing hot producer gas thus formed in direct heat transfering relationship with a body of coal to preheat and carbonize the same, periodically shutting 0H." the How of hot producer gas in heat transferring relation with the thus carbonized coal body and admitting steam to said coal body and thereby cooling the body and generatin water gas, causing the resultant water gas and excess steam to pass into and through the incandescent charge of fuel in the producer and thereby forming more hot water gas, discharging the carbonized coal body and conducting the resultant hot mixture of water gas and producer gas in direct heat transferring relationship with another bod of coal and thereby distilling the volatiles from the coal, removing the resultant mixture of Water gas, producer gas and coal gas from the second coal body, and periodically reversing the direction of flow of gas through the coal bodies. l

3. The process of producing mixed water gas, producer gas and coal gas and of carbonizing fuel which comprises continuously air-blasting hot solid carbonaceous fuel and thus continuously generating hot producer gas, periodically passing a stream of the hot producer gas through a heat absorbing structure andfin heat transferring relationship with a body of solid carbonaceous fuel to preheat the same and thence in heat transferring relationship with a charge of solid carbonaceous fuel in a coking retort and thereby carbonizing the same, shutting off the' flow of said producer gas stream and passing steam, into the retort charge to generate hot water gas, discharging the carbonized retort charge, urther heating the water gas thus formed in the structure previously heated by the producerl gas stream, and passing the hot water gas admixed with hot producer gas from such producer through coal in a separate coking retort to coke and distil coal contained in said retort.

4. A process for producing fuel gas and carbonized coal which comprlses continuously passing air through a hot coke body in a gas producer and t ereby generating producer gas, passin hot producer gas thus formed downwardly through a stationary body of coal in a coking retort and thereby carbonizing the coal, subsequently passing steam upwardly through the thus carbonized hot coal and thence into said hot coke bodyl and thereby generating water gas, and discharging the carbonized coal passing the resulting hot producer and water gases from the producer downwardly through another body of coal and thereby carbonizing the same.

5. A process of producing fuel gas and carbonized solid fuel which comprises, air blasting hot solid carbonaceous fuel, in a gas producer and thereby generating producer gas, simultaneously passing steam in series, through a separate body of hot solid carbonaceous`fuel and thence into said producer fuel charge and thereby generating water as, and passing the resulting mixture of ot water gas and producer gas thus formed from said producer to and through a body of solid carbonizable fuel in a retort and thereby carbonizing the same.-

6. A process of producing fuel gasand carbonized solid fuel which comprises, continuously forming producer gas by continuously air blasting hot solid carbonaceous fuel in a gas producer, storing a part of the sensible heat of the producer'gas thus formed in a heat storage body and utilizing another part of the sensible heat of said gas in carbonizin a stationary body of solid carbonizable fue passing steam throu hthe body of fuel thus carbonized and there yv generating water gas, passing the water gas thus formed and any excess steam through the hot heat storage body and thence into and through said producer fuel charge and thereby generating hot Water gas, and utilizing the sensible heat of such water gas in carbonizing another body of said solid carbonizable fuel.

7. A process of producing fuel gas and carbonized coal which comprises, forming hot producer gas by air blasting hot solid carbonaceous fuel in a gas producer, abstracting a portion of the heat from said producer gas and storing said heat in a heat storage body, heating and carbonizing coal by means of heat remaining in'said producer gas, and subsequently passing steam through said hot carbonized coal and thence through said heat storage body into and through said producer fuel body to thereby enerate water gas.

8. A process of pro ucing fuel gas and carbonized solid fuel which comprises, forming hotl producer gas by air blasting hot solid carbonaceous fuel in a gas producer, simultane- Y ously passing steam through a hot heat 'Storage body and thence through the charge of hot fuel in said producer, passing the resulting mixture of hot producer and water gases.

formed from said producer through another heat storage body to heat the same, periodically reversin the relation of said heat storage bodies to t e flow of steam and gas to and from said producer, and passing the hot gases formed in said producer from said heat storage bodies through a body of solid carbonizable fuel and thereby carbonizing the same and enriching the gas mixture with the Volatile products of carbonization.

9. A process of producing fuel gas and carbonized solid fuel which comprises, forming a hot producer gas by air blasting hot solid carbonaceous fuel in a* as producer, passing a portion of the hot pro ucer gas thus formed downwardly through a stationary body of solid carbonizable fuel in a retort and thereby carbonizing the same, and utilizinglthe sensible heat of another portion of said producer gas in preheating air used for blasting said producer fuel charge. I

10. A process of producing fuel gas and carbonized solid fuel which comprises, continuouslyv forming producer gas by continuously air blasting hot solid carbonaceous fuel in a gas producer, passing. a portion of the hot producer gas thus formed downwardly throu h a statlonar body of solid carbonizable uel and there y carbonizing the same, back-steaming the thus carbonized fuel body to quench the same and generate water gas, passing the resulting water gas and excess steam through the producer fuel charge and thereby generating additional hot Water gas, passing the hot water gas thus formed together with producer gas from the producer downwardly through another stationary body of solid carbonizable fuel to carbonize the same, and utilizing; the sensible heat of a portion of the hot producer gas formed in the producer in preheating blast air supplied to the reducer.

11. i process of producing fuel gas and carbonizedl solid fuel which comprises, forming hot producer gas by air blasting hot solid carbonaceous fuel in a gas producer, utilizing the sensible heat of part of the producer gas thus formed to prcheat air and fuel supplied to said producer, and utilizing the sensible heat of another portion of the producer gas thus formed to carbonize by direct heat a stationary charge of solid carbenizable fuel in a coking retort.

12. A method of producing fuel' gas and carbonized solid fuel which comprises, continuously blasting a charge of solid carbone ceous fuel in a gas producer with air and thereby forming hot producer gas, passing hot producer gas thus formed downwardly through a stationary charge of solid carbonizable fuel in a retort and thereby carbonizing the same, quenching the thus-carbonized fuel with steam and passing the resultant hot steam and water gas into the producer fuel charge for further water gils reactions theren in, and discharging the carbonized fuel from one retort while simultaneously carbonizing a charge of said carbonizable fuel in another retort by passing hot producer gas and water gas thereby produced from said producer downwardly therethrough.

13. A method of producing fuel gas and carbonized coal which comprises, continuously air-blasting a charge of solid carbona ceous fuel in a gas producer and thereby forming hot roducer gas, removing the ash component o the fuel from the producer in the form of liquid slag, passing hot producer gas formed from said producer downwardly through a stationary body of coal of small cross sectional area in a retort and thereby carbonizing the same, withdrawing producer gas admixed with vaporized hydrocarbons from the bottom of the retort, back-steaming the retort charge afterA its carbonization is complete and thereby generating water gas, and passing the water gas 'thus formed together with the hot producer gas through another stationary charge of coal in another retort and thereby carbonizing said last named retort charge.

14. A method of producing fuel gas and carbonized coal which comprises, continuousl blasting a charge of solid carbonaceous fiiel in a gas producer with air and thereby generating hot producer gas, passing hot producer gas thus'formed in heat transferring relationship with a stationary body of coal of comparatively small cross-sectional area in a retort and thereby carbonizing the coal, uenching the retort charge with steam and tiereby generating water gas, passing `the resulting water gas and any excess steam into the producer fuel body for further Water gas making reactions therein, and passing the hot water gas product of said reactions together with producer gas formed in the pro ducer in direct heat transferring relationship with another stationary body of coal of comparatively small cross-sectional area and thereby carbonizing said coal.

In testimony whereof l alliu my signature.

nlVllLlBUR G. LAIRD. 

